Does that mean that we are supposed to exclude Bf 110C in 1939 from discussion?
It is debatable. My quote
In fact who had such aircraft in April of 1939
From website ;
Messerschmitt Bf 110
Ten C-0 pre-production aircraft were delivered for evaluation in January 1939 with Bf110C-1 production aircraft following soon after. As production ramped up, both Focke-Wulf and Gotha joined the programme and by the end of
August 1939 some 159 models had been delivered with a production rate of
thirty per month. By the end of the year, 315 aircraft had been produced.
Now is that just 110C production or did the August total include the 45 100Bs? In any case how many 110Cs were available in April and who England knew what about them?
Accounts and book are all over the place, one old book claims there were 10 Grouppes of 110s used in Poland.
Wiki says that 102 Bf 110s were used at the start of Poland?
Weed out prototypes and trainers?
So further research may be needed?
While the 110 first flew in may of 1936 (almost a year before the hypothetical conversation in post #82) there was no photo of it available to the British in early 1938, The 1938 Janes has a two sentence description and no photo or drawing.
So when did the British have any real idea of it's capabilities?
I'm flabbergasted that the AM made a judgement mistake.
As we both know, they made a bunch of them
This decision might not have been one of them. The failure to push for the promised replacement aircraft for the Fulmar was probably a bigger one. Remember the Fulmar was just supposed to fill in (even in 1937 planning) for the plane/s the FAA really wanted.
Earlier investment in drop tanks would've been prudent. Hopefully we should not wait for a foreign precedent for that idea.
Drop tanks in peacetime may not have been a good idea. The idea of landing aircraft on carriers with partially filled detachable tanks wasn't likely to find favor

For the aircraft operating from shore looking for carriers using drop tanks, a bit safer. But where in the mission does the engagement take place?
And can the fighter with drop tank keep up with the bombers without them?
The last certainly depends on which aircraft and what year.
Views on drop tanks certainly changed and the hardware (racks, fittings, mechanisms) undoubtedly got better.
For hypotheticals, the Luftwaffe could have been a much more effective force if the supply of DB 601 engines had been much greater in 1939/40.
The Do 17V-8 flew with DB 600 engines.
Post #82 also had
we need a fighter that is equal in performance to anything the Europeans, Soviets, Americans or Japanese are currently flying, plus whatever we know about what they're designing for tomorrow. This fighter must also be robust, easily maintained, with easy-to-fold wings (no origami please), with good landing characteristics and forward visibility for carrier ops. We must have long endurance and a heavy armament to kill the strike aircraft and their escorts well away from our carriers. And with seven current carriers and six of the new armoured deck carriers under construction or planned, with likely two or three of the smaller, older carriers removed from service, we'll need at least two hundred to two hundred and fifty of these fighters, plus trainers and spares.
"I see, thanks for stating your points so clearly. Well how about this? The RAF will be switching over to the new Hurricane and Spitfire, so why don't you take their obsolete Gladiators? Plus [snark], how about a twin-seat bomber-derived design that doesn't meet any of your requirements for close shore combat; here's our idea (presents sketch of the failed Fairey P.4/34 that first flew in Jan 1937).
Bolded parts seem to be in disagreement.
The "
failed Fairey P.4/34" suggestion had 4 hours of endurance (or about twice the range of a Hurricane or Spitfire) and twice the ammo of either the Hurricane or Spitfire at the time.
Part in Italics is what is in question.
For the Americans they had ordered 77 P-35s in June of 1936 but the first was not delivered until mid 1937 (after this hypothetical discussion) and the last of the 77 is delivered in August of 1938. While they have a range of 1000-1150 miles on internal fuel they have a top speed of 282mph and are armed with one .50 cal gun and one .30 cal gun.
The sealants used on the "wet wing" that gave such range also tended to dry out and cause leaks. I have no idea if the British knew of this.
In July of 1937 the US Army ordered 210 Curtiss P-36s. The first P-36 is delivered to the US army in April of 1938.